1. Field of the Invention
The present invention relates to a method and apparatus for cleaning waste gas generated from power generating machines, industrial facilities, incinerators, etc., and more particularly to a method and apparatus for reducing harmful ingredients contained in the waste gas by dissociating the ingredients by irradiation with gas laser and electron beams thereto.
2. Description of the Prior Art
Korean Patent Application Laid-Open No. 96-21112 discloses a conventional method and apparatus for treating waste gas by irradiation with electron beams. According to this method and apparatus, ammonia is added to the waste gas mainly containing sulfuric oxide (SO.sub.x) or nitrogen oxide (NO.sub.x), and then the sulfuric oxide and nitrogen oxide are changed to ammonium sulfate and ammonium nitrate by irradiation of electron beams thereto, so that the harmful ingredients, i.e., SO.sub.x and NO.sub.x, are eliminated from the exhaust gas. In such a method using ammonia gas for eliminating the harmful ingredients, however, the ammonia gas is apt to be exhausted together with the exhaust gas under an incomplete reaction of the above-described ingredients. Further, this method and apparatus has problems of necessitating a separate apparatus for mixing ammonia with the waste gas as well as uneven irradiation of electron beams into the waste gas.
U.S. Pat. No. 4,915,916 discloses a method and apparatus for treating waste gas by irradiation with electron beams without using ammonia. According to this method and apparatus, a part of the waste gas to be treated is irradiated with electron beams to form active species such as [O] and OH.sup.-- radicals, and the waste gas having the active species is dispersed into and mixed into the remaining waste gas to change NO.sub.x and SO.sub.x in the waste gas into the form of a mist or dust by the action of the active species. The mist or dust is then captured by a dust collector. However, this method and apparatus has problems such as a low efficiency of eliminating the harmful ingredients and a large size of the apparatus since the electron beam irradiation region is separated from the reaction region.
The conventional apparatuses and methods for treating harmful gas with electron beams as described above also have drawbacks such that the electron beam irradiation region does not cover the entire path of the waste gas, and a low density of electron beams results in a low speed and efficiency of eliminating the harmful ingredients.